1. Field of the Invention
This invention relates to a process for the catalytic hydrogenation of a fatty acid.
2. Description of the Prior Art
Fatty alcohols, particularly the higher alcohols, are important commodities in the chemical industry whose uses as such and as intermediates are legion. The bulk of the fatty alcohols commercially available at present are producted synthetically either by the OXO process or in accordance with Ziegler chemistry. These methods employ the higher terminal olefins and ethylene, respectively, as the primary feed stocks. Since these feed stocks are petroleum derived, their costs have mounted so considerably of late that renewed interest is currently being focused on the reductive conversion of fatty acids to the corresponding alcohols which to date has only been used to produce certain specialty alcohols not available by the indicated synthetic routes.
The persistent problem with the method for the catalytic hydrogenation of a fatty acid to the alcohol is that the processing conditions involved in terms of temperature and pressure, particularly the latter, are exceedingly strenuous. The source of this problem resides in the catalyst itself. For years attention has been principally directed toward enhancing the catalytic activity of copper values for this purpose. More recently, however, rhenium has been proposed as an effective catalyst requiring less strenuous processing conditions than the more effective copper catalysts which had hitherto been developed. The supporting published data in respect of this finding are noteworthy and are reported by H. Smith Broadbent et al. in J. Org. Chem., 24, 1847 (1959).
As acknowledged, rhenium itself is quite effective as a catalyst in carrying out the indicated hydrogenation method under acceptably tolerable pressure conditions. Beyond this, however, rhenium results in excellent selectivity toward the formation of the desired product. Notwithstanding the foregoing, improvement of the catalyst's capability to provide higher yield conversion levels is desirably called for. Accordingly, the foremost objective of this invention is to enhance the catalytic activity of rhenium metal in a manner whereby improved conversion yields are realized as compared with the use of said catalyst alone.